Protector for electric circuits

ABSTRACT

A terminal of an electric power-supplying fuse has an opening therein and has an annular mounting surrounding that opening; and that annular mounting supports, in cantilever fashion, the indicator-bearing terminal of an indicating fuse. The other terminal of that indicating fuse is displaced radially outwardly of and out of engagement with the fusible element of the powersupplying fuse. The indicating fuse is a wholly enclosed, complete subassembly which is manufactured and tested, and is then assembled with said annular mounting on said terminal.

United States Patent Inventor Aloysius J. Fister St. Louis, Mo.

Appl. No. 62,414

Filed Aug. 10, 1970 Patented Oct. 19, 1971 Assignee McGraw-EdisonCompany Elgin, Ill.

PROTECTOR FOR ELECTRIC CIRCUITS [56] References Cited UNITED STATESPATENTS 2,639,350 5/1953 Cox 337/244 3,244,839 4/1966 Albright 337/1593,301,979 1/1967 Fister 337/231 3,483,502 12/1969 Mikulecky 337/244Primary Examinerl-larold Broome Attorney-Rogers, Ezell, Eilers & RobbinsABSTRACT: A terminal of an electric power-supplying fuse has an openingtherein and has an annular mounting surrounding that opening; and thatannular mounting supports, in can- 9 Claims 4 Drawing Figs tileverfashion, the indicator-bearing terminal of an indicating U.S.Cl 337/244,fuse. The other terminal of that indicating fuse is displaced 337/159,337/231 radially outwardly of and out of engagement with the fusibleInt. Cl "1101b 85/30 element of the power-supplying fuse. The indicatingfuse is a Field of Search 337/244, wholly enclosed, complete subassemblywhich is manufac- 158, 159, 186, 192,2l4,227,231,236, 241,267, tured andtested, and is then assembled with said annular PROTECTOR FOR ELECTRICCIRCUITS This invention relates to improvements in Protectors forElectric Circuits. More particularly, this invention relates toimprovements in indicator-equipped, power-supplying electric fuse.

It is, therefore, an object of the present invention to provide animproved indicator-equipped, power-supplying electric fuse.

Power-supplying fuses are frequently equipped with indicators, and thoseindicators can be very useful. Unfortunately,

however, the indicators of some indicator-equipped, powersupplyingelectric fuses are fabricated as parts of the terminals of those fuses;and it takes more time and money to fabricate and test these indicatorsthan it takes to manufacture and test commercially produced indicatingfuses. Consequently, it would be desirable to provide anindicator-equipped, powersupplying electric fuse which utilized acommercially produced indicating fuse as the indicator thereof. Thepresent invention provides such an indicator-equipped, power-supplyingelectric fuse; and it does so by forming one of the terminals of thatindicator-equipped, power-supplying electric fuses with an opening thatis surrounded by an annular mounting which receives and supports theindicator-bearing terminal of a commercially produced indicating fuse.That indicating fuse can be produced and tested at less cost, and with ahigher degree of accuracy, than can the indicators for manyindicator-equipped power-supplying electric fuse which has a terminalwith an opening surrounded by an annular mounting that receives andsupports the indicator-bearing terminal of a commercially producedindicating fuse.

' The opening in the terminal of the indicator-equipped,

, power-supplying electric fuse provided by the present invention islocated eccentrically of the geometric center of that electric fuse.This is desirable; because it bodily spaces the indicator of thatindicating fuse away from the fusible element of the power-supplyingelectric fuse, and thereby keeps that indicator fuse from derating thatpower-supplying electric fuse. Also, the eccentric location of thatindicating fuse makes it possible to displace the indicator of thatindicating fuse an appreciable distance away from the base of anyU-shaped clip in which the power-supplying electric fuse will be held.It is, therefore, an object of the present invention to displace theindicating fuse of an indicator-equipped, power-supplying electric fuseeccentrically away from the fusible element of that power-supplyingelectric fuse.

Other and further objects and advantages of the present invention shouldbecome apparent from an examination of the drawing and accompanyingdescription.

In the drawing and accompanying description two preferred embodiments ofthe present invention are shown and described but it is to be understoodthat the drawing and accompanying description are for the purpose ofillustration only and do not limit the invention and that the inventionwill be defined by the appended claims.

In the drawing,

FIG. I is a partially broken-away, partially sectional elevational viewof one preferred embodiment of indicatorequipped power-supplyingelectric fuse that is made in accordance with the principles andteachings of the'present invention,

FIG. 2 is a sectional view through the electric fuse of FIG. 1, and itis taken along the plane indicated by the line 2-2 in FIG. 1,

FIG. 3 is a sectional view, on a larger scale, of a sleeve of insulationwhich is supported by, and which extends outwardly from, .the free endof an indicating fuse which can be substituted for the indicating fuseshown in FIGS. 1 and 2, and

FIG. 4 is a sectional view through the electric fuse of FIG. 1, and itis taken along the plane indicated by the line 4--4 in FIG. 1.

Referring to the drawing in detail, the numeral 20 generally denotes anindicator-equipped, power-supplying electric fuse that is made inaccordance with the principles and teachings of the present invention.That fuse has an elongated tubular housing 22 of insulating material, adthat housing has openings 21 adjacent the left-hand end thereof and hasopenings 23 adjacent the right-hand end thereof. A ferrulelike terminal24 is telescoped over the left-hand end of the housing 22; and the freeedge 26 of that ferrulelike tenninal is flared outwardly, as shown byFIG. 1. A number of openings 28 are formed in the cylindrical portion ofthe ferrulelike terminal 24; and those openings are in register with theopenings 21 in the housing 22. An opening 31 is provided at thegeometric center of the closed end of the ferrulelike terminal 24; andsolder 33 secures the closed end of a U-shaped bracket 30 to the innersurface of the closed end of the ferrulelike terminal 24 adjacent thatopening. The arms of that U-shaped bracket extend inwardly of thehousing 22, as shown by FIGS. 1 and 4. A further opening is fonned inthe closed end of the ferrulelike terminal 24, and an annular mounting32 surrounds and helps define that opening; and that annular mountingextends inwardly of the housing 22, as shown by FIG. 1.

The numeral 34 denotes a ferrulelike terminal that telescopes over theright-hand end of the housing 22; and the free edge 36 of thatferrulelike terminal is flared outwardly, as shown by FIG. 1. Openings38 are provided in the cylindrical portion of the ferrulelike terminal34; and those openings are in register with the openings 23 in thehousing 22. An opening 39 is provided at the geometric center of theclosed and of the ferrulelike terminal 34; and solder 41 secures theclosed end of a U-shaped bracket 40 to the inner surface of the closedend of the ferrulelike terminal 34 adjacent that opening. The arms ofthat U-shaped bracket extend inwardly of the housing 22, as shown'byFIG. 1. The arms of the bracket 40 are in register with the arms of thebracket 30, and those brackets are at the geometric center of thehousing 22.

The numeral 42 denotes an elongated support; and that support preferablyis made from a suitable insulating material. That support is shown asbeing cruciform in cross section; but it could be given any desiredcross section. The opposite ends of the support 42 are disposed between,and supported by, the arms of the brackets 30 and 40. The unstressedspacing between the arms of the bracket 30 is smaller than the distancebetween the outer faces of one arm of a cruciform cross section of thesupport 42; but those arms will yield to permit those outer faces to bepressed into position between those arms. Thereafter, the restorativeforces within the arms of the bracket 30 will cause those arms to gripand hold the left-hand end of the support 42. The unstressed spacingbetween the arms of the bracket 40 is smaller than the distance betweenthe outer faces of the said one arm of the cruciform cross section ofsupport 42; but those arms will yield to permit those outer faces to bepressed into position between those arms. Thereafter, the restorativeforces within the arms of the bracket 40 will cause those arms to gripand hold the right-hand end of the support 42.

The numeral 44 denotes a fusible element which has the left-hand endthereof electrically connected to the inner surface of the closed end offerrulelike terminal 24 by solder, not shown; and that fusible elementhas the right-hand thereof electrically connected to the inner surfacesof the closed end of ferrulelike terminal 34 by solder, not shown. Thatfusible element is wound onto the support 42 in generally helical form;and the turns of that fusible element are fixedly held, relative to thehousing 22, by that support.

The numeral 46 denotes an enclosed, self-contained, commerciallymanufactured and commercially tested indicating fuse; and thatindicating fuse has a casing of insulating material and has twoferrulelike terminals at the opposite ends of that casing. One of thoseferrulelike terminals supports a nor mally retracted indicator 48; butthat indicator will be moved outwardly to indicating position wheneverthe indicating fuse 46 is blown. The left-hand ferrulelike terminal ofindicating fuse 46 is pressed into, and is aligned and supported by, theannular mounting 32 on the closed end of the ferrulelike terminal 24.Solder 52 electrically connects the ferrulelike terminal 24 of thepower-supplying electric fuse 20 to the left hand ferrulelike terminalof the indicating fuse 46. A sleeve 50 of insulation encases theright-hand ferrulelike terminal of the indicating fuse 46', and thatsleeve will keep that ferrulelike terminal from electrically engagingthe fusible element 44 of the power-supplying electric fuse. in doingso, that sleeve keeps that indicating fuse from derating thatpower-supplying electric fuse. The annular mounting 32 will, in everyinstance where the indicating fuse 46 is properly assembled with theferrulelike terminal 24, align the axis of that indicating fuse with theaxis of the support 42and will thereby automatically space theright-hand terminal of that indicating fuse away from, and radiallyoutwardly of, the fusible element 44. However, in the event an assemblerwere, somehow, to improperly assemble the indicating fuse 46 with theannular mounting 32, and were to cause the right-hand terminal of thatindicating fuse to incline toward one or more turns of the fusibleelement 44, the sleeve 50 of insulating material would prevent anyelectrical contact between that right-hand terminal and any turns ofthat fusible element.

The U-shaped bracket 30 will be fixedly secured to the inner surface ofthe closed end of the ferrulelike terminal 24; and it will hold theleft-hand end of the support 42 fixed relative to that closed end. Theannular mounting 32 is fixed relative to the U-shaped bracket 30; and itwill hold the left-hand terminal of the indicating fuse 46 fixedrelative to that closed end. in that way, the U-shaped bracket 30 andthe annular mounting 32 automatically provide and maintain the desiredspacing between the left-hand end of the support 42 and the left-handterminal of the indicating fuse 46.

The numeral 54 denotes an elongated, normally infusible conductor whichhas the right-hand end thereof electrically connected to the innersurface of the closed end of ferrulelike terminal 34 by solder, notshown. That conductor has the major portion of the length thereof woundonto the support 42 in generally helical fashion; and the turns of thatconductor are disposed between adjacent turns of the fusible conductor44, so the turns of conductor 54 never engage the turns of fusibleelement 44. The left-hand end of the conductor 54 is soldered to theright-hand terminal of the indicator fuse 46. The normally infusibleconductor 54 coacts with the indicator fuse 46 to constitute onecontinuous, electrical path between the ferrulelike tenninals 24 and 34;and the fusible element 44 constitutes a second continuous electricalpath between those ferrulelike terminals.

Arc-extinguishing filler material 56 is introduced into the housing 22before the last of the two ferrulelike terminals 24 and 34 is assembledwith that housing. Pins 58 are passed through the openings 28 in thecylindrical portion of the ferrulelike terminal 24 and through theopenings 21 in the housing 22 to fixedly secure that ferruleliketerminal to that housing. Pins 60 are passed through the openings 38 inthe cylindrical portion of the ferrulelike tenninal 34 and through theopenings 23 in the housing 22 to fixedly secure that ferruleliketerminal to that housing.

The effective resistance of the fusible element 44 of thepower-supplying electric fuse is very much less than the total effectiveresistance of indicating fuse 46 and normally infusible conductor 54. Asa result, as long as the fusible element 44 remains intact, that fusibleelement will conduct substantially all of the current which flowsbetween the ferrulelike terminals 24 and 34; and hence not enoughcurrent will flow through the indicating 46 to blow" that indicatingfuse. However, when the power-supplying electric fuse 20 is subjected toa heavy overload or a short circuit, the fusible element 44 will heat toits melting temperature and will fuse. At such time, the overload orshort circuit" current will attempt to flow throughserially connectedindicating fuse 46 and normally infusible conductor 54; but the fusibleelement of that indicating fuse will promptly fuse. Thereupon a spring,not show, within that indicating fuse will force the indicator 48 ofthat indicating fuse to move outwardly of the ferrulelike terminal 42 ofthe power-supplying electric fuse 20. That indicator will provide aquick and certain indication, to a maintenance man,

that the power-supplying electric fuse 20 has interrupted the circuit.

The indicating fuse 46 can be any on e of a number of commerciallyproduced and commercially tested small ampere indicating fuses that arebeing marketed. Such indicating fuses are made by mass productionmethod, and they are tested as they are produced. As a result, thoseindicating fuses are relatively inexpensive, and they have carefullycontrolled and carefully tested electrical characteristics. The annularmounting 32 enables that indicating fuse from any stresses to which itmight be subjected if it were mechanically connected to the support 42.Also, that annular mounting spaces that indicating fuse wholly away fromthe fusible element 44, and thereby keeps that indicating fuse fromderating the power-supplying electric fuse 20.

Referring particularly to FIG. 3, the numeral 70 denotes and indicatingfuse which can be similar to the indicating fuse 46, but which willusually have a smaller ampere rating than that of indicating fuse 46.The left-hand terminal of the indicating fuse 70 will support anindicator, not shown, which is similar to the indicator 48. A sleeve 72of insulating material is telescoped over the right-hand terminal of theindicating fuse 70; and that sleeve extends a substantial distancebeyond that terminal. A tubular washer 74 of that washer abuts theclosed end of the right-hand terminal of the indiating fuse 70. A disk76, which supports a metal arc-gap terminal 78, abuts the right-handface of the tubular washer 74; and that disk holds the left-hand end ofthat metal arc-gap terminal in register with the central portion of theright-hand terminal of indicating fuse 70. A mass of insulatingmaterial, such as an epoxy plastic, fills the right-hand end of themetal arc-gap terminal 78 and the left-hand end of a normally infusibleconductor 82 which is fixedly secured to the right-hand end of thatmetal arc-gap terminal. The normally infusible conductor 82 can besimilar to the normally infusible conductor 54, although it may have adifferent overall resistance.

The indicating fuse 70 will have the left-hand terminal thereof held byan annular mounting similar to the annular mounting 32 in FIG. 1; andthat annular mounting will support that indicating fuse incantileverlike fashion. THe right-hand terminal of the indicating fuse70 will normally be displaced from, and spaced radially outwardly, ofthe, fusible element of the power-supplying electric fuse in which theindicating fuse 70 is mounted. However, in the event an assembler failsto properly insert the left-hand terminal of the indicating fuse 70within the annular mounting therefore, the sleeve 72 of insulation willkeep the right-hand terminal of that indicating fuse from electricallyengaging the fusible element of that powersupplying electric fuse.

As long as the fusible element of the power-supplying electric fuse, ofwhich the indicating fuse 70 is a part, remains intact, that fusibleelement will carry substantially all of the current flowing through thatpower-supplying electric fuse; and hence, not enough current will flowthrough the indicating fuse 70 to "blow" that indicating fuse. However,when that fusible element responds to a heavy overload or to a shortcircuit to fuse, the voltage across the power-supplying electric fusewill cause an arc to develop across the spark gap between the arc-gapterminal 78 and the right-hand terminal of the indicating fuse 70. Thatspark will cause sufficient energy to pass through the fusible elementof that indicating fuse to cause that fusible element to fuse.Thereupon, the indicator, not shown, of that indicating fuse will moveoutwardly to indicating position, and will thereby indicate that thepowersupplying electric fuse had opened the circuit.

The indicating fuse 70, like the indicating fuse 46 of FIG. 1, will bean enclosed, self-contained, commercially produced and commerciallytested indicating fuse. As a result, that indicating fuse will berelatively inexpensive, and it will have carefully controlled andcarefully tested electrical characteristics. In addition, thatindicating fuse can easily be assembled with a fuse terminal by havingthe indicator-bearing thereof pressed into an annular mounting on thatfuse terminal.

Because the power-supplying electrical fuse uses a commercially producedand commercially tested indicating fuse, a manufacturer of thatpower-supplying electric fuse does not need to rate and test theindicating fuses for different sizes of that power-supplying electricfuse. Instead, that manufacturer need only rate and test the fusibleelement 44 for any desired size of power-supplying electric fuse 20, andthen select the appropriate size of indicating fuse 46 or 70. As aresult, it is simple and inexpensive to design and make any desiredampere rating of the power-supplying electric fuse 20.

Whereas the drawing and accompanying description have shown anddescribed two preferred embodiments of the present invention, it shouldbe apparent to those skilled in the art that various changes may be madein the form of the invention without aflecting the scope thereof.

What I claim is:

l. A power-supplying electric fuse which has a housing, a terminaladjacent one end of said housing, a terminal adjacent the other end ofsaid housing, a fusible element electrically connecting said terminals,an opening in the first said terminal, an annular mounting on said firstsaid terminal surrounding said opening ans extending inwardly of saidfirst said terminal and extending inwardly of said housing, an enclosedself-contained indicating use which has a casing of insulating materialand which has terminals at the opposite ends of said casing and whichhas one of said terminals telescoped within said annular mounting, theindicator of said indicating fuse normally being held in retractedposition within said one terminal of said indicating fuse, saidindicating fuse being supported in cantilever fashion by said annularmounting and having the other terminal of said indicating fuse beingdisplaced radially outwardly of, and out of engagement with, saidfusible element, said indicating fuse having said first said terminal bysaid annular mounting, said fusible element normally carryingessentially all of the current flowing between said terminals of saidpower-supplying fuse and thus normally enabling said indicator of saidindicating fuse to be held in nonindicating position, said indicatingfuse responding to the fusing of said fusible element to cause saidindicator thereof to move outwardly to indicating position.

2. A power-supplying electric fuse which has a housing, a terminaladjacent one end of said housing, a terminal adjacent the other end ofsaid housing, a fusible element electrically connecting said terminals,an opening in the first said terminal, an annular mounting on said firstsaid terminal surrounding said opening and extending inwardly of saidfirst said terminal and extending inwardly of said housing, and enclosedself-contained indicating fuse which has a casing of insulating materialand which has terminals at the opposite ends of said casing and whichhas one of said terminals telescoped within said annular mounting, theindicator of said indicating fuse normally being held in retractedposition within said one terminal of said indicating fuse, saidindicating fuse being supported in cantilever fashion by said annularmounting and having the other terminal thereof disposed inwardly of saidhousing said other terminal of said indicating fuse being displacedradially outwardly of, and out of engagement with, said fusible element,said indicating fuse having said indicator thereof held in register withsaid opening in said first said terminal by said annular mounting, saidfusible element normally carrying essentially all of the current flowingbetween said terminals of said power-supplying fuse and thus normallyenabling said in dicator of said indicating fuse to be held innonindicating posi tion, said indicating fuse responding to the fusingof said fusible element to cause said indicator thereof to moveoutwardly to indicating position, said annular mounting having the axisthereof parallel to, but displaced radially outwardly of, the geometricaxis of said housing of said power-supplying electric fuse.

3. A power-supplying electric fuse which has a housing, a terminaladjacent one end of said housing, a terminal adjacent the other end ofsaid housing, a fusible element electrically connecting said terminals,and opening in the first said terminal, an annular mounting on saidfirst said terminal surrounding said opening and extending inwardly ofsaid first said terminal and extending inwardly of said housing, anenclosed self-contained indicating fuse which has casing of insulatingmaterial and which has terminals at the opposite ends of said casing andwhich has a one of said terminals telescoped within said annularmounting, the indicator of said indicating fuse normally being held inretracted position within said one terminal of said indicating fuse,said indicating fuse being supported in cantilever fashion by saidannular mounting and having the other terminal thereof disposed inwardlyof said housing, said other terminal of said indicating fuse beingdisplaced radially outwardly of, and out of engagement with, saidfusible element, said indicating fuse having said indicator thereof heldin register with said opening in said first said terminal by saidannular mounting, said fusible element normally carrying essentially allof the current flowing between said terminals of said power-supplyingfuse and thus normally enabling said indicator of said indicating fuseto be held in nonindicating position, said indicating fuse responding tothe fusing of said fusible element to cause said indicator thereof tomove outwardly to indicating position, said annular mounting beingadjacent the inner surface of said housing of said power-supplyingelectric fuse and thus being eccentric of the geometric axis of saidhousing of said power-supplying electric fuse, whereby said indicatingfuse can be spaced an appreciable distance from the base of a U-shapedclip for said first said terminal of said power-supplying electric fuse.

4. A power-supplying electric fuse as claimed in claim 1 wherein solderengages said annular mounting and said one terminal of said indicatingfuse to electrically bond said one terminal of said indicating fuse tosaid first terminal of said power-supplying electric fuse.

5. A power-supplying fuse which has a housing, a terminal adjacent oneend of said housing, a terminal adjacent the other end of said housing,a fusible element electrically connecting said terminals, an opening inthe first said terminal, an annular mounting on said first said terminalsurrounding and extending inwardly of said first said terminal andextending inwardly of said housing, and enclosed self-containedindicating fuse which has a casing of insulating material and which hasterminals at the opposite ends of said casing and which has terminals atthe opposite ends of said casing and which has one of said terminalstelescoped within said annular mounting, the indicator of saidindicating fuse normally being held in retracted position within saidone terminal of said indicating fuse, said indicating fuse beingsupported in cantilever fashion by said annular mounting and having theother terminal thereof disposed inwardly of said housing, said otherterminal of said indicating fuse being displaced radially outwardly of,and out of engagement with, said fusible element, said indicating fusehaving said indicator thereof held in register with said opening in saidfirst said terminal by said annular mounting, said fusible elementnormally carrying essentially all of the current flowing between saidtenninals of said power-supplying fuse and thus normally enabling saidindicator of said indicating fuse to be held in nonindicating position,said indicating fuse responding to the fusing of said fusible element tocause said indicator thereof to move outwardly to indicating position, asleeve of insulation encasing said other terminal of said indicatingfuse, and said sleeve of insulation keeping said other terminal of saidindicating fuse from engaging any part of said fusible element of saidpower-supplying electric fuse.

6. A power-supplying electric fuse as claimed in claim 1 wherein anelongated support of insulating material is disposed between saidterminals of said power-supplying electric fuse, wherein said fusibleelement of said power-supplying electric fuse, wherein said fusibleelement of said power-supplying electric fuse is wound onto saidelongated support, and wherein mounting brackets at the inner faces ofsaid terminals of said power-supplying electric fuse hold and supportthe ends of aid elongated support.

7. A power-supplying electric fuse which has a housing, a terminaladjacent one end of said housing, a terminal adjacent the other end ofsaid housing, a fusible element electrically connecting said terminals,an opening in the first said terminal, an annular mounting on said firstsaid terminal surrounding said opening and extending inwardly of saidfirst said terminal and extending inwardly of said housing, an enclosedself-contained indicating fuse which has a casing of insulating materialand which has terminals at the opposite ends of said casing and whichhas one of said terminals telescoped within said annular mounting, theindicator of said indicating fuse normally being held in retractedposition within said one terminal of said indicating fuse, saidindicating fuse being supported in cantilever fashion by said annularmounting and having the other terminal thereof disposed inwardly of saidhousing, said other terminal of said indicating fuse being displacedradially outwardly of, and out of engagement with, said fusible element,said indicating fuse having said indicator thereof held in register withsaid opening in said first said terminal by said annular mounting, saidsaid fusible element normally carrying essentially all of the currentflowing between said terminals of said power-supplying fuse and thusnormally enabling said indicator of said indicating fuse responding tothe fusing of said fusible element to cause said indicator thereof tomove outwardly to indicating position, an elongated support ofinsulating material disposed between said terminals of saidpowersupplying electric fuse, said fusible element of saidpower-supplying electric fuse being wound into said elongated support,and mounting brackets at the inner faces of said terminals of saidpower-supplying electric which hold and support the ends of saidelongated support, the mounting bracket at the inner face of said firstsaid terminal of said power-supplying electric fuse being fixedly spacedfrom said annular mounting on said first said terminal of saidpower-supplying electric fuse, whereby said mounting bracket at theinner face of said first said terminal of said power-supplying electricfuse will coact with said annular mounting on said first said terminalof said power-supplying electric fuse to hold said one terminal of saidindicating fuse a fixed and predetermined distance from the adjacent endof said elongated support.

8. A power-supplying electric fuse which has a housing, a terminaladjacent one end of said housing, a terminal adjacent the other end ofsaid housing, a fusible clement electrically connecting annularterminal, an opening in the first said disposed an annular mounting onsaid first said terminal surrounding said opening and extending inwardlyof said first said terminal and extending inwardly of said housing, anenclosed self-contained indicating fuse which has a casing of insulatingmaterial and which has terminals at the opposite ends of said casing andwhich has one of said terminals telescoped within said annular mounting,the indicator of said indicating fuse normally being held in retractedposition within said one terminal of said indicating fuse, saidindicating fuse being supported in cantilever fashion by said annularmounting and having the other terminal thereof disposed inwardly of saidhousing, said other terminal of said indicating fuse being displacedradially outwardly of, and out of engagement with, said fusible element,said indicating fuse having said indicator thereof held in register withsaid opening in said first said terminal by said annular mounting, saidfusible element normally carrying essentially all of the current flowingbetween said position, of said power-supplying fuse and thus normallyenabling said indicator of said indicating fuse to be held innonindicating position, said indicating fuse responding to the fusing ofsaid fusible element to cause said indicator thereof to move outwardlyto indicating position, a sleeve of insulation encasing said otherterminal of said indicating fuse, and insulating washer within saidsleeve of insulation spacing a disk from said carries an arc-gapterminal in spaced relation tosaid other terminal of said indicatingfuse, said arc-gap terminal and said other terminal of said indicatingfuse being bridged by an arc whenever said fusible element of saidpower-supplying electric fuse is fused, and said are causing saidindicating fuse to permit said indicator thereof to move outwardly toindicating position.

9. A power-supplying electric fuse which has a housing, a

terminal adjacent one end of said housing, a terminal adjacent the otherend of said housing, a fusible element electrically connecting saidterminals, an elongated support of insulating material disposed betweensaid terminals, said fusible element being wound onto said elongatedsupport, and mounting brackets at the inner faces of said tenninals,said mounting brackets holding and supporting the ends of said elongatedsupport and thereby fixing the positions of said ends of said elongatedsupport relative to said terminals, said mounting brackets havingsupport-engaging surfaces with unstressed spacings therebetween whichare smaller than the width of said elongated support, whereby saidsupport-engaging surfaces of said brackets must be stressed as said endsof said elongated support are moved intoengagement with said mountingbrackets, the restorative forces developed within said mounting bracketsas said mounting brackets are so stressed thereafter holding saidelongated support fixed relative to said mounting brackets and thusfixed relative to said housing.

1. A power-supplying electric fuse which has a housing, a terminaladjacent one end of said housing, a terminal adjacent the other end ofsaid housing, a fusible element electrically connecting said terminals,an opening in the first said terminal, an annular mounting on said firstsaid terminal surrounding said opening ans extending inwardly of saidfirst said terminal and extending inwardly of said housing, an enclosedself-contained indicating use which has a casing of insulating materialand which has terminals at the opposite ends of said casing and whichhas one of said terminals telescoped within said annular mounting, theindicator of said indicating fuse normally being held in retractedposition within said one terminal of said indicating fuse, saidindicating fuse being supportEd in cantilever fashion by said annularmounting and having the other terminal of said indicating fuse beingdisplaced radially outwardly of, and out of engagement with, saidfusible element, said indicating fuse having said first said terminal bysaid annular mounting, said fusible element normally carryingessentially all of the current flowing between said terminals of saidpower-supplying fuse and thus normally enabling said indicator of saidindicating fuse to be held in nonindicating position, said indicatingfuse responding to the fusing of said fusible element to cause saidindicator thereof to move outwardly to indicating position.
 2. Apower-supplying electric fuse which has a housing, a terminal adjacentone end of said housing, a terminal adjacent the other end of saidhousing, a fusible element electrically connecting said terminals, anopening in the first said terminal, an annular mounting on said firstsaid terminal surrounding said opening and extending inwardly of saidfirst said terminal and extending inwardly of said housing, and enclosedself-contained indicating fuse which has a casing of insulating materialand which has terminals at the opposite ends of said casing and whichhas one of said terminals telescoped within said annular mounting, theindicator of said indicating fuse normally being held in retractedposition within said one terminal of said indicating fuse, saidindicating fuse being supported in cantilever fashion by said annularmounting and having the other terminal thereof disposed inwardly of saidhousing said other terminal of said indicating fuse being displacedradially outwardly of, and out of engagement with, said fusible element,said indicating fuse having said indicator thereof held in register withsaid opening in said first said terminal by said annular mounting, saidfusible element normally carrying essentially all of the current flowingbetween said terminals of said power-supplying fuse and thus normallyenabling said indicator of said indicating fuse to be held innonindicating position, said indicating fuse responding to the fusing ofsaid fusible element to cause said indicator thereof to move outwardlyto indicating position, said annular mounting having the axis thereofparallel to, but displaced radially outwardly of, the geometric axis ofsaid housing of said power-supplying electric fuse.
 3. A power-supplyingelectric fuse which has a housing, a terminal adjacent one end of saidhousing, a terminal adjacent the other end of said housing, a fusibleelement electrically connecting said terminals, and opening in the firstsaid terminal, an annular mounting on said first said terminalsurrounding said opening and extending inwardly of said first saidterminal and extending inwardly of said housing, an enclosedself-contained indicating fuse which has casing of insulating materialand which has terminals at the opposite ends of said casing and whichhas a one of said terminals telescoped within said annular mounting, theindicator of said indicating fuse normally being held in retractedposition within said one terminal of said indicating fuse, saidindicating fuse being supported in cantilever fashion by said annularmounting and having the other terminal thereof disposed inwardly of saidhousing, said other terminal of said indicating fuse being displacedradially outwardly of, and out of engagement with, said fusible element,said indicating fuse having said indicator thereof held in register withsaid opening in said first said terminal by said annular mounting, saidfusible element normally carrying essentially all of the current flowingbetween said terminals of said power-supplying fuse and thus normallyenabling said indicator of said indicating fuse to be held innonindicating position, said indicating fuse responding to the fusing ofsaid fusible element to cause said indicator thereof to move outwardlyto indicating position, said annular mounting being adjacent the innersurface of said housing of saId power-supplying electric fuse and thusbeing eccentric of the geometric axis of said housing of saidpower-supplying electric fuse, whereby said indicating fuse can bespaced an appreciable distance from the base of a U-shaped clip for saidfirst said terminal of said power-supplying electric fuse.
 4. Apower-supplying electric fuse as claimed in claim 1 wherein solderengages said annular mounting and said one terminal of said indicatingfuse to electrically bond said one terminal of said indicating fuse tosaid first terminal of said power-supplying electric fuse.
 5. Apower-supplying fuse which has a housing, a terminal adjacent one end ofsaid housing, a terminal adjacent the other end of said housing, afusible element electrically connecting said terminals, an opening inthe first said terminal, an annular mounting on said first said terminalsurrounding and extending inwardly of said first said terminal andextending inwardly of said housing, and enclosed self-containedindicating fuse which has a casing of insulating material and which hasterminals at the opposite ends of said casing and which has terminals atthe opposite ends of said casing and which has one of said terminalstelescoped within said annular mounting, the indicator of saidindicating fuse normally being held in retracted position within saidone terminal of said indicating fuse, said indicating fuse beingsupported in cantilever fashion by said annular mounting and having theother terminal thereof disposed inwardly of said housing, said otherterminal of said indicating fuse being displaced radially outwardly of,and out of engagement with, said fusible element, said indicating fusehaving said indicator thereof held in register with said opening in saidfirst said terminal by said annular mounting, said fusible elementnormally carrying essentially all of the current flowing between saidterminals of said power-supplying fuse and thus normally enabling saidindicator of said indicating fuse to be held in nonindicating position,said indicating fuse responding to the fusing of said fusible element tocause said indicator thereof to move outwardly to indicating position, asleeve of insulation encasing said other terminal of said indicatingfuse, and said sleeve of insulation keeping said other terminal of saidindicating fuse from engaging any part of said fusible element of saidpower-supplying electric fuse.
 6. A power-supplying electric fuse asclaimed in claim 1 wherein an elongated support of insulating materialis disposed between said terminals of said power-supplying electricfuse, wherein said fusible element of said power-supplying electricfuse, wherein said fusible element of said power-supplying electric fuseis wound onto said elongated support, and wherein mounting brackets atthe inner faces of said terminals of said power-supplying electric fusehold and support the ends of aid elongated support.
 7. A power-supplyingelectric fuse which has a housing, a terminal adjacent one end of saidhousing, a terminal adjacent the other end of said housing, a fusibleelement electrically connecting said terminals, an opening in the firstsaid terminal, an annular mounting on said first said terminalsurrounding said opening and extending inwardly of said first saidterminal and extending inwardly of said housing, an enclosedself-contained indicating fuse which has a casing of insulating materialand which has terminals at the opposite ends of said casing and whichhas one of said terminals telescoped within said annular mounting, theindicator of said indicating fuse normally being held in retractedposition within said one terminal of said indicating fuse, saidindicating fuse being supported in cantilever fashion by said annularmounting and having the other terminal thereof disposed inwardly of saidhousing, said other terminal of said indicating fuse being displacedradially outwardly of, and out of engagement with, said fusible element,said indicating fuse having said indicator thereof held in register withsaid opening in said first said terminal by said annular mounting, saidsaid fusible element normally carrying essentially all of the currentflowing between said terminals of said power-supplying fuse and thusnormally enabling said indicator of said indicating fuse responding tothe fusing of said fusible element to cause said indicator thereof tomove outwardly to indicating position, an elongated support ofinsulating material disposed between said terminals of saidpower-supplying electric fuse, said fusible element of saidpower-supplying electric fuse being wound into said elongated support,and mounting brackets at the inner faces of said terminals of saidpower-supplying electric which hold and support the ends of saidelongated support, the mounting bracket at the inner face of said firstsaid terminal of said power-supplying electric fuse being fixedly spacedfrom said annular mounting on said first said terminal of saidpower-supplying electric fuse, whereby said mounting bracket at theinner face of said first said terminal of said power-supplying electricfuse will coact with said annular mounting on said first said terminalof said power-supplying electric fuse to hold said one terminal of saidindicating fuse a fixed and predetermined distance from the adjacent endof said elongated support.
 8. A power-supplying electric fuse which hasa housing, a terminal adjacent one end of said housing, a terminaladjacent the other end of said housing, a fusible element electricallyconnecting annular terminal, an opening in the first said disposed anannular mounting on said first said terminal surrounding said openingand extending inwardly of said first said terminal and extendinginwardly of said housing, an enclosed self-contained indicating fusewhich has a casing of insulating material and which has terminals at theopposite ends of said casing and which has one of said terminalstelescoped within said annular mounting, the indicator of saidindicating fuse normally being held in retracted position within saidone terminal of said indicating fuse, said indicating fuse beingsupported in cantilever fashion by said annular mounting and having theother terminal thereof disposed inwardly of said housing, said otherterminal of said indicating fuse being displaced radially outwardly of,and out of engagement with, said fusible element, said indicating fusehaving said indicator thereof held in register with said opening in saidfirst said terminal by said annular mounting, said fusible elementnormally carrying essentially all of the current flowing between saidposition, of said power-supplying fuse and thus normally enabling saidindicator of said indicating fuse to be held in nonindicating position,said indicating fuse responding to the fusing of said fusible element tocause said indicator thereof to move outwardly to indicating position, asleeve of insulation encasing said other terminal of said indicatingfuse, and insulating washer within said sleeve of insulation spacing adisk from said carries an arc-gap terminal in spaced relation to saidother terminal of said indicating fuse, said arc-gap terminal and saidother terminal of said indicating fuse being bridged by an arc wheneversaid fusible element of said power-supplying electric fuse is fused, andsaid arc causing said indicating fuse to permit said indicator thereofto move outwardly to indicating position.
 9. A power-supplying electricfuse which has a housing, a terminal adjacent one end of said housing, aterminal adjacent the other end of said housing, a fusible elementelectrically connecting said terminals, an elongated support ofinsulating material disposed between said terminals, said fusibleelement being wound onto said elongated support, and mounting bracketsat the inner faces of said terminals, said mounting brackets holding andsupporting the ends of said elongated support and thereby fixing thepositions of said ends of said elongated support relative to saidterminals, said mounting brackets having support-engaging surfaces withunstressed spacings therebetween which are smaller than the width ofsaid elongated support, whereby said support-engaging surfaces of saidbrackets must be stressed as said ends of said elongated support aremoved into engagement with said mounting brackets, the restorativeforces developed within said mounting brackets as said mounting bracketsare so stressed thereafter holding said elongated support fixed relativeto said mounting brackets and thus fixed relative to said housing.